Should I start learning on an acoustic guitar first?

To begin with it makes little difference whether you are learning on an acoustic or an electric since all guitars have the same notes and work in more or less the same way, the main difference being how the sound is amplified. Obviously certain styles of music are associated with certain types of guitar, but in the beginning it is not too important which you use. What is more important is that you feel comfortable with the guitar you are playing. i.e. it is of a suitable size for your body and hands. Very young children may struggle on a full-size electric or acoustic since they will not be able to reach the end of the guitar. For this reason it is better for them to use a half-size or three quarter-size guitar.